In tableau there are few options for ranking that we are using, like RANK_UNIQUE,
It assigns the same ranking value for the categorical variables that have the same label name.
For better understanding you need a example:
If you had rows where 2 categories were the same, like "Office Supplies" appeared twice, then with RANK_UNIQUE if you were ranking on the sales function, then you'd get a 2 or 3 (or whatever the rank is) appear for both rows
In your context you can likely get away with the standard RANK function: